Climate Change Harming Polar Bear Cubs

Polar bear litters are decreasing in size due to sea ice decline resulting from climate change, according to a study published in Nature on February 8, 2011. If this trend continues as predicted, the polar bear population could be in serious jeopardy.

“Species everywhere are feeling the heat, but none more extreme than polar bears and other Arctic species,” said Geoff York, WWF’s polar bear expert.

Polar bears use their sea ice habitat to hunt their main prey, seals. As the sea ice melts at a faster pace, polar bears have less chance to build up the necessary body weight for when they come to land and hibernate – this is especially true for pregnant females. The survival of cubs during pregnancy and infancy is closely linked to the amount of energy pregnant females have stored up before denning during the winter months.

The study, which WWF supported, found that if spring sea ice break-up occurs one month earlier than usual, 40-73 percent of pregnant females could fail to bring cubs to term. Their projection climbs to 55-100 percent if the sea ice break-up occurs two months earlier than usual.

Arctic sea ice has been melting at alarming rates in recent decades and projections show no sign of it slowing. The National Snow and Ice Data Center reported that, in January 2010, Arctic sea ice was at its lowest January level since satellite records began in 1979, while the air temperatures over much of the region were 4 to 11 degrees Fahrenheit higher than normal.

Scientists attribute these rising temperatures to the buildup of carbon pollution in the atmosphere from the burning of fossil fuels. “Unless we take action to curb climate change and transition to low-carbon energy sources like renewable energy, we will consign our planet to a very perilous path,” said York.

Learn more about how we can shift our energy choices to reduce climate impacts

Polar bears were listed as a threatened species under the Endangered Species Act during the Bush administration in 2008. The listing is a clear indication that climate change impacts are already threatening the survivability of animals and habitats, and illustrates the urgency of preparing for and adapting to a rapidly changing climate.